A numerical study on performance efficiency of a low-temperature horizontal ground-source heat pump system
A numerical study on performance efficiency of a low-temperature horizontal ground-source heat pump system
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DOI：
10.1016/j.enbuild.2023.113137
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发表时间：
2023-05
影响因子：
6.7
通讯作者：
W. Gao;S. Masum;Meysam Qadrdan;Hywel Rhys Thomas
中科院分区：
文献类型：
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作者：
W. Gao;S. Masum;Meysam Qadrdan;Hywel Rhys Thomas
浅层地下及其低品位热潜力的开发是设计第五代区域供热和供冷（DHC）网络的基础。水平式地源热泵系统是利用浅层地热能的一种常用方式。对HGSHP系统的性能和浅层地下热行为的现实估计和预测应考虑整个系统，包括建筑物的加热和冷却负荷，热泵和地下换热器，和地面。这应该伴随着现实的大气和地面条件。本文采用全系统方法，建立了具有真实边界条件的三维热工水力耦合模型。动态热泵性能系数（COP），取决于季节变化的加热/冷却需求和地面条件也被考虑。模型的验证进行了文献中的实验和分析结果。该模型被应用于评估HGSHP系统，以支持在英国的一个潜在的网站上的第五代DHC网络的发展。几个影响因素，如地面水分传输，建筑热负荷模式，埋深的地面环路，和初始地面温度分布进行了研究，以评估HGSHP系统的性能效率和地面热行为的演变，响应于热提取或拒绝到地面。结果表明，采用200个埋深为3 m的U型地下环路，以纯水为热载体，设计的HGSHP系统可满足该地区月总需热量的5%。忽略土壤水分迁移或夸大土壤饱和度会高估土壤源热泵系统的承载能力。与纯制热模式相比，制热制冷模式下的热泵性能系数更高，系统效率更高。预测的HGSHP系统的性能提高与埋深的地面回路。结果还表明，原状地温每增加1 ℃，就可满足该场地月总需热量的8%。
Exploitation of shallow ground and its low-grade heat potential is fundamental to designing 5th generation district heating and cooling (DHC) networks. Horizontal ground-source heat pump (HGSHP) systems are a common way to utilize shallow geothermal energy. Realistic estimation and prediction of performance of a HGSHP system and shallow ground thermal behaviour should consider the whole system including building heating and cooling load, heat pump and ground heat exchanger, and the ground. This should be accompanied by realistic atmospheric and ground conditions. In this paper, a three-dimensional coupled thermal–hydraulic model with realistic boundary conditions adopting a whole system approach is presented. Dynamic heat pump coefficient of performance (COP) that depends on seasonal variation of heating/cooling demand and ground conditions are also considered. Model validations are conducted against experimental and analytical results in literatures. The model is applied for evaluating a HGSHP system to support development of a 5th generation DHC network on a potential site in the UK. Several influencing factors, such as ground moisture transfer, building thermal load mode, buried depth of ground loops, and initial ground temperature profile are studied to assess performance efficiency of the HGSHP system and evolution of ground thermal behaviour in response to heat extraction or rejection into the ground. The results show that 5% of the monthly total heat demand of the site could be met by the designed HGSHP system, consisting of 200 U-shaped ground loops buried at the depth of 3 m and pure water as the heat carrier. Overlooking the ground moisture transfer or hyperbolizing the ground saturation would overestimate the load-carrying capacity of the HGSHP system. The HGSHP system is more efficient with a higher heat pump COP under the heating and cooling mode than under the heating-only mode. Predicted performance of the HGSHP system improves with buried depth of the ground loops. The results also show that a 1 ℃ increase in the undisturbed ground temperature could suffice up to 8% of the monthly total heat demand of the site.